Carlton Fairweather was unhappy with referee Billy Khatib as Sunderland Ladies lost for the first time in eight games.
Manchester City inflicted the Lady Black Cats’ first defeat since April when they won the Continental Tyres Cup match at Hetton 3-1.
It was a blow to Sunderland’s hopes of progressing in the competition where the top two sides progress from each group.
Fairweather’s side are third in the five-team group, behind Man City and Liverpool, and above Women’s Super League 2 sides Everton and Durham, who they have beaten to date.
While the head coach acknowledged the quality of Manchester City, who fielded a team packed with England stars, he felt his side did not get a fair crack of the whip from referee Billy Khatib.
Sunderland had an early shout for a penalty rejected when Gemma Wilson appeared to be pushed in the area, while in injury time the same player was adjudged to have brought down Nikita Parris.
Toni Duggan’s spot-kick was despatched past Rachael Laws to clinch a 3-1 victory.
“There was those things but on top of that there were times our players were blatantly pulled back by some of their players without even a word,” said Fairweather.
“I’m disappointed by that.
“The referee was very poor.
“Obviously you want to do the very best you can in every game you play, so I’m disappointed for the girls that the refereeing was as bad as it was.”
Fairweather said he attempted to speak to the official, without success.
“I tried but the ref ran inside,” said the 53-year-old.
While there was a sense of frustration over the refereeing, Fairweather was not unhappy with his players.
Sunderland trailed to two goals in the first 15 minutes to Parris and England skipper Steph Houghton but fought back with a header by Wilson from a Vicky Greenwell corner.
But they could not find an equaliser, with the Duggan penalty taking the match away from them three minutes into added time.
“We were playing against world-class players and the game was always going to be tough,” he said.
“Until the penalty in injury time we kept ourselves in the game.
“We caused them problems without creating any real clear-cut chances, but I was pleased that we kept ourselves in the game.”